1. Field of the Invention
This invention relates to a data entry keyboard apparatus of the kind including an array of key switches connected between row and column conductors, and associated control means connected to said row and column conductors for detecting the actuation of a key switch and providing an output signal representing an actuated key switch.
2. Description of the Prior Art
Data entry keyboard apparatuses of the kind specified are generally known and find application in various devices, for example, computer entry terminals, ATM's (Automated Teller Machines) and EFTPOS (Electronic Funds Transfer at Point of Sale) terminals.
Frequently, such known data entry keyboard apparatuses are utilized for the entry of information which should remain confidential to the person entering the information on the keyboard, for example, a customer PIN (Personal Identification Number) which may be used to identify the customer by a keyboard entry in an ATM or EFTPOS terminal.
However, the known apparatuses have the disadvantage that it is possible for an unauthorized person to attach electrical "tapping" connections to the keyboard conductors or to the electrical leads which connect the keyboard to the control circuitry, and by monitoring such tapping connections, the unauthorized person may ascertain confidential information subsequently entered into the keyboard.